1. Field of the Invention
This invention relates to improvements in wet-rope or rope-wick applicators especially for applying herbicides to weeds, and to improved methods of applying herbicides.
The applicators of the invention can be used to apply any type of liquid or solution to growing plants. The applicators are especially suited to applying herbicides to weeds in a growing crop where the weeds are taller than the crop.
2. Description of the Prior Art
Australian Registered Designs Nos. 84 620, 84 659, 84 660, 84 661, 84 685, 84 656 and 84 687 illustrate hand-held wet-rope applicators in which a rope-wick is supplied from a tubular reservoir by gravity feed.
U.S. Pat. Nos. 4,187,638 and 4,219,964 disclose rope-wick applicators in which rope-wicks are woven through holes in cylindrical reservoirs, the wicks draw herbicide from the reservoirs by capilliary action. The cylindrical reservoirs are supported by a boom and drawn by a tractor or the like to bring the wicks into physical contact with the weeds and the herbicide or herbicide solution is wiped on to the weeds from the wick.
U.S. Pat. Nos. 1,368,123, 1,523,590, 1,764,952, 1,818,369, 2,123,988, 2,311,782, 2,458,027, 2,530,234, 2,769,668, 2,979,757, 2,946,154, 3,002,319, 3,021,642, 3,077,701, 3,184,888, 4,027,986, 4,291,491 and 4,305,224; and 910,933, 1,109,060 and 1,527,669 all disclose herbicide or liquid applicators having a reservoir which feeds liquid to a rope-wick, the liquid flowing to the wick by gravitational or capillary action; the second group are similar to the first group of patents except that instead of rope-wicks they embody an apron type of wick.
U.S. Pat. Nos. 1,507,595, 3,198,396, 3,651,600 and 4,019,278 disclose liquid applicators comprising reservoirs having supply line(s) to a cylindircal reservoir with a transverse longitudinal axis. The cylindrical reservoir has a series of holes through to the outside surface which is covered with an absorbent material. These devices operate using gravity; absorbtion and pumping action.
Further, U.S. Pat. Nos. 2,935,818 and 4,208,835 disclose liquid applicators comprising reservoirs and pumps to spray a liquid onto a revolving cylindrical applicator. The cylindrical applicator is covered with an absorbtive material which imparts the liquid to surfaces that come into contact with it.
U.S. Pat. No. 3,320,694 describes a liquid applicator having a reservoir and pump means to spray liquid onto plants.
Australian Patent Application No. 62043/80 describes another type of rope-wick applicator in which two parallel cylindrical reservoirs each supply different ends of a series of parallel rope-wicks which extend from the cylindrical reservoirs at an angle to them. The cylindrical reservoirs are supplied from a master reservoir and supported on a frame such that when drawn by a tractor or the like with the axes of the cylindrical reservoirs perpendicular to the direction of movement the rope-wicks sweep diagonally across the weeds wiping herbicide or herbicide solution on to them.
The known applicators described above all have three major disadvantages. Because of the gravity or capilliary feed, an operator using those applicators cannot vary supply of herbicide when treating an area where the density of weeds is variable other than by varying tractor speed or, in the case of hand-held applicators going over and over thicker clumps of weeds. Again, because of the gravity or capilliary feed, the prior art applicators tend to allow the herbicide to drip on to the crop or desirable plants especially when the applicators are stationary. Herbicide must be mixed by operators of the prior art applicators with the resultant dangers in handling toxic materials. Spraying methods tend to apply liquid to all plants and are thus not as selective in their use to eradicate weeds, as compared with wiping methods. Spraying methods also endanger operators or other persons, by allowing these persons to come into contact with the airborne and windborne liquids and herbicides.